To me, the real meaning of The Year of Mercy can be easily understood by reflecting on the parable of the prodigal son.
In his foolishness, the young man distanced himself from the love of his father and went far away and squandered all his money with others of his sort. He impoverished himself to the extent that he had no decent food to eat except that given to pigs.
In his distress, his thoughts went back to the goodness of his loving father. He resolved to return to him with haste, never doubting for a minute his forgiveness. He found his father waiting for him with open arms and even wanted to celebrate the return of his beloved son.
The compassion shown by the father was unlimited and so was his joy to see his lost son once again. This is the mercy shown to us, sinners, by our eternal Father, whenever we return to Him after repenting. Divine mercy, indeed.